LAN9353 Datasheet, PDF (515/523 Pages) Microchip Technology – Interfaces at up to 200Mbps via Turbo MII

LAN9353
20.7 Clock Circuit
The device can accept either a 25 MHz crystal or a 25 MHz single-ended clock oscillator (±50 ppm) input. If the single-
ended clock oscillator method is implemented, OSCO should be left unconnected and OSCI should be driven with a
clock signal that adheres to the specifications outlined throughout Section 20.0, "Operational Characteristics". See
Table 20-13 for the recommended crystal specifications.
TABLE 20-13: CRYSTAL SPECIFICATIONS
PARAMETER
Crystal Cut
Crystal Oscillation Mode
Crystal Calibration Mode
Frequency
802.3 Frequency Tolerance at
25^oC
802.3 Frequency Stability Over
Temp
802.3 Frequency Deviation Over
Time
802.3 Total Allowable PPM Bud-
get
Shunt Capacitance
Load Capacitance
Drive Level
SYMBOL
F_fund
F_tol
F_temp
F_age
C_O
C_L
P_W
Equivalent Series Resistance
R₁
Operating Temperature Range
OSCI Pin Capacitance
OSCO Pin Capacitance
MIN
NOM
MAX
AT, typ
Fundamental Mode
Parallel Resonant Mode
-
25.000
-
-
-
±40
UNITS NOTES
MHz
ppm
Note 28
-
-
±40
ppm
Note 28
-
±3 to 5
-
ppm
Note 29
-
-
±50
ppm
Note 30
-
-
300
Note 31
-
Note 32
-
-
-
-
-
-
-
3 typ
3 typ
7
pF
18
pF
-
µW
100
Ω
Note 33
o_C
-
pF
Note 34
-
pF
Note 34
Note 28: The maximum allowable values for frequency tolerance and frequency stability are application dependent.
Since any particular application must meet the IEEE ±50 ppm Total PPM Budget, the combination of these
two values must be approximately ±45 ppm (allowing for aging).
Note 29: Frequency Deviation Over Time is also referred to as Aging.
Note 30: The total deviation for 100BASE-TX is ±50 ppm.
Note 31: The minimum drive level requirement P_W is reduced to 100 uW with the addition of a 500 Ω series resistor,
if C_O 5 pF, C_L 12 pF and R180 Ω
Note 32: 0 °C for commercial version, -40 °C for industrial version
Note 33: +70 °C for commercial version, +85 °C for industrial version
Note 34: This number includes the pad, the bond wire and the lead frame. PCB capacitance is not included in this
value. The OSCI pin, OSCO pin and PCB capacitance values are required to accurately calculate the value
of the two external load capacitors. The total load capacitance must be equivalent to what the crystal
expects to see in the circuit so that the crystal oscillator will operate at 25.000 MHz.
 2015 Microchip Technology Inc.
DS00001925A-page 515